The present invention relates generally to dental devices used to position a dowel pin during the forming of a jaw reproduction.
In the making of artificial teeth, caps, crowns and other prosthetic devices, it is accepted practice to initially make a dental impression of the jaw or pertinent portion of the jaw. The impression is a negative of the jaw and teeth. A positive reproduction of the jaw and teeth is subsequently formed by the deposit of casting material in the impression which material is vibrated to enhance the quality of the reproduction. To enable removal and insertion of a tooth model from the reproduction during the manufacture and sizing of the prosthetic article, a dowel pin is positioned in the negative impression in centered relationship with the defective tooth impression whereupon a pour of casting material is made embedding the lower portion of the pin. A second pour is usually super-imposed on the first pour. Upon the material setting, the reproduction is removed from the impression and inverted whereupon a sawing operation serves to isolate the tooth model or models enabling their removal and precise repeated placement and fitting of the prosthetic device during fabrication of same. It is obvious that precise dowel pin placement in the tooth impression is necessary both for tooth model removal as well as for subsequent fitting of the prosthetic device during its manufacture.
Disclosed in the prior art are pin supporting means which attach to the impression tray or a tray supporting stand as found in U.S. Pat. Nos. 2,836,849; 3,277,576; 3,639,985 and 3,717,933. Other prior art has utilized pin supporting means which instead of attaching to the tray insertably engages the impression material as per U.S. Pat. Nos. 3,521,354 and 3,553,839.
In the known prior art it is customary to incidentally subject the dowel pin and its supporting arrangement to vibration during vibration of the plaster laden impression which not uncommonly results in dowel pin displacement. Remedying such displacement, if discernable, is often done in an imprecise manner. As earlier noted, precise dowel pin location is of prime interest for subsequent prosthetic fabrication.